数字雨效果

在黑客帝国电影场景中，曾出现大量的数字雨特效。在现实的生活中，雨往往给人一种清新的感觉，而雨后的感觉则是新生。
也许，电影中所表达的意思便是对自我的启迪乃至新生的过程。

代码如下所示：

#include <stdio.h>
#include <graphics.h>
// 窗口的宽和高
#define WIDTH 960
#define HEIGHT 640
#define STR_SIZE 25	 // 数字雨数组最大存储
#define STR_NUM 128	 // 数字雨的串数
#define STR_WIDTH 15 // 字符串宽度
// 雨的结构
struct Rain {
	int x;
	int y;
	int speed;			// 下降速度
	char str[STR_SIZE];	// 数字雨数组
}rain[STR_NUM];

char CreateCh() {
	char temp = 0;
	int flag = rand() % 3;
	if (flag == 0) {
		temp = rand() % 26 + 'a';
	} else if (flag == 1) {
		temp = rand() % 26 + 'A';
	} else {
		temp = rand() % 10 + '0';
	}
	return temp;
}

void GameInit() {
	// 初始化基础数据
	for (size_t i = 0; i < STR_NUM; i++) {
		rain[i].x = i * STR_WIDTH;
		rain[i].y = rand() % HEIGHT;
		rain[i].speed = (rand() % 5) + 5;
	}
	// 初始化字符串
	for (size_t i = 0; i < STR_NUM; i++) {
		for (size_t j = 0; j < STR_SIZE; j++) {
			rain[i].str[j] = CreateCh();
			if (rain[i].y > HEIGHT) {
				rain[i].y = 0;
			}
		}
	}
}

void GameDraw() {
	cleardevice();
	for (size_t i = 0; i < STR_NUM; i++) {
		for (size_t j = 0; j < STR_SIZE; j++) {
			outtextxy(rain[i].x, rain[i].y - STR_WIDTH * j, rain[i].str[j]);
			settextcolor(RGB(0, 255 - (13 * j), 0));
		}
	}
}

void GamePlay() {
	for (size_t i = 0; i < STR_NUM; i++) {
		rain[i].y += rain[i].speed;
		if (rain[i].y - STR_SIZE * STR_WIDTH > WIDTH) {
			rain[i].y = 0;
		}
	}
}

void ChangeCh() {
	for (size_t i = 0; i < STR_NUM; i++) {
		rain[rand() % STR_NUM].str[rand() % STR_SIZE] = CreateCh();
	}
}

int main() {
	initgraph(WIDTH, HEIGHT);
	srand(GetTickCount());
	DWORD t1, t2;
	t1 = t2 = GetTickCount();
	GameInit();
	while (true) {
		BeginBatchDraw();
		GameDraw();
		ChangeCh();
		if (t2 - t1 > 20) {	// 使游戏下落延时
			GamePlay();
			t1 = t2;
		}
		t2 = GetTickCount();	
		EndBatchDraw();
		// Sleep(20); // 使整个程序延时
	}
	getchar();
	closegraph();
	return 0;
}